TiO2 Mesocrystals Processed at Low-temperature as the Electron-transport Material in Perovskite Solar Cells.

TiO2 is the most widely used material for preparing the electron-transporting layer (ETL) in perovskite solar cells (PSCs), however, it requires a high-temperature sintering process. Besides, the intrinsic defects and low electron mobility of TiO2 ETL will cause the instability and hysteresis effect of PSCs. In the present work, the mesoporous film composed of TiO2 mesocrystals was facilely fabricated via low temperature route and then used as an ETL in PSCs for the first time, and a satisfying efficiency of 20.26% can be achieved under the delicate control in the entire fabricated procedures of the device. Moreover, the optimal device with an area of 1 cm2 also achieved an efficiency of 17.07%. Comparing to the common TiO2, TiO2 mesocrystals ETLs shows the enhancement of electron extraction and suppression of the charge accumulation at the interface of perovskite/ETL, resulting in the improvement of photovoltaic performance and reduction of hysteresis effect.